Designated Driver
by Thalia Marie Grace
Summary: [It's Isabelle's twenty-first birthday, and she's hosting a party. She also can't figure out why Clary does not want to drink any alcohol.] "Maybe she's pregnant." Alec teases, slipping his arm around Clary's shoulders. "You're pregnant?" Isabelle demands loudly. [Turns out Clary is just the designated driver. T.]


**Author's Note: So...I still have massive writer's block for Nine Steps Back. And Project Marriage isn't getting updated until Project Carrot is over, so I can upload both epilogues at the same time. And Project Carrot is taking forever because I'm just slow and lazy.**

**But I found a life-saving little blog on Tumblr with prompts and they totally gave me cute ideas for oneshots.**

**Just for a little clarification, this is AU. And since we don't know when Isabelle's birthday is (unless it's been stated and I have no idea), I'm saying that it's in December, and that she's younger than Clary by four months.**

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><p><strong>Designated Driver<strong>

Isabelle Lightwood has outdone herself yet again—and this time, it's in the style of her own twenty-first birthday party.

"Happy birthday, Izzy," says Clary Morgenstern, smiling brightly at her best friend. She gives the dark-haired girl a hug as she steps inside with her boyfriend (Isabelle's older brother, Jace) behind her. "How does it feel to finally be able to legally drink?"

"No different than the past three years of my life that I've been illegally drinking." Isabelle responds, cracking a smile back. "We're putting the coats in the guest room next to mine."

"I'll go put them in there." Jace offers, kissing his sister's cheek as he removes his coat and takes his girlfriend's from her hands.

"Come on." Isabelle says, dragging Clary into the kitchen where the drinks are set up. "What do you want? I'll fix you something myself."

"Water." Clary requests, leaning against the counter. "Or milk. Or apple juice. Or pop."

Isabelle blinks. She stares at her best friend. "With, like, vodka in it?"

"Non-alcoholic." the redhead clarifies.

"I get it." Isabelle tosses Clary a bottle of water, shrugging. "It's pretty early. You don't want to drink until later. That's cool."

"No, I mean...at all."

Isabelle's expression is extremely confused.

"Hey, Clary." Alec says brightly, giving her a side-hug. "I didn't see you come in, but—Isabelle, what's up?"

"Clary is refusing alcohol." Isabelle says slowly. "Why is that? What's going on? Clary, I knew you were responsible and all, but you are twenty-one. You can drink legally."

"Maybe she's pregnant." Alec teases, slipping his arm around Clary's shoulders.

"You're _pregnant?" _Isabelle demands loudly. Clary hears the guests in the living room go silent.

"Shut _up_, Isabelle!" Clary hisses. Her cheeks are red. "I'm not pregnant!"

Isabelle's mouth forms into an 'o'. She flushes from embarrassment. "Sorry. I shouldn't have shouted that. Or assumed that."

Clary's eyebrows are raised. "You think?"

"Sorry, sorry." Isabelle bites her lip. "Come on, let's go join the party. I think we've got everyone here."

But it only gets worse. The minute Clary leaves the kitchen with Isabelle and Alec, Jace slips his arm around her waist. "So is there something you want to tell me?" he asks teasingly.

"What—no!" Clary punches his side. "I'm not pregnant!"

"I was _joking_, babe," says Jace, but he's laughing as he kisses her temple. "Where did Isabelle even get that idea?"

"Because I didn't want any alcohol." she waves the water bottle.

He raises his eyebrow. "Did you tell her that you're my ride back to our place?"

"Well...no. I didn't really have a chance."

"You should probably tell her that."

"I probably should." Clary muses. She leans against him and opens the water bottle. "Maybe later."

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><p>"It's been three hours and you still haven't taken any shots or drank any alcohol at all." Isabelle is pouting. "Seriously, Clary, what's up? Are you sure you're not pregnant or something? If you are, it's totally cool—I mean, I would <em>love <em>to be an aunt and you and Jace have been dating for a long enough time and—"

"Isabelle." Clary places her hands on the black-haired girl's shoulder. "I'm not pregnant. I'm driving Jace and I home."

Isabelle blinks. "Why don't you just stay here for the night? Then you can drink!"

"I also have an exam tomorrow," says the redhead. "And I don't want to have to take it hungover."

"Fair enough." Isabelle sighs. "But seriously, Clary, I'd really be all for being an aunt. Or your sister-in-law. Just saying."

Clary is blushing as she says, "Shut up, Isabelle."

"Okay, okay!" she puts her hands up in surrender. "As of right now, that topic is officially dropped. I'm gonna go see if I can find Simon, 'cause I lost him somewhere and I can't really find him."

Clary decides that Isabelle is at least a little bit tipsy as the birthday girl pushes through the crowd, searching for her boyfriend.

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><p>"I can count on one hand the number of people who <em>didn't <em>ask me when the due date was tonight." Clary says irritably, parking the car and unbuckling her seatbelt.

"Don't let what Izzy said get to you, babe." Jace says reassuringly, getting out of the car and shutting the door behind him. Despite being able to, he did not drink much at the party. "Listen; Alec's obviously older and she expected him to be married with at least one kid by now, but obviously that's not going to happen, because he and Magnus aren't really into adopting at the moment. And you know she absolutely adores babies. Just the _thought _of being able to be the aunt of one makes her excited."

"I'm not blaming her." Clary shuts the garage and enters the dark house, flipping on the lights as she hangs up her coat and kicks off her shoes. "I just wish she wouldn't have said that loudly."

"You know, there's something Isabelle said to me before we left that's just not sitting right with me." Jace follows her upstairs, yawning.

"What's that?" Clary is pulling on her pyjama pants.

"She said to make sure I didn't keep you up because of your exam tomorrow." Jace's eyebrows are furrowed. "Clary, honey, you don't _have _an exam tomorrow. You've been off of school for a few days now."

"Isabelle told me we could have just stayed there and spent the night and that way I could have gotten drunk with her." Clary explains, slipping into bed and turning off her lamp. "That was the first excuse that popped into my mind."

Jace slides into bed beside her. "We could have done that. Why didn't we? You were looking forward to having a fun time with Izzy tonight."

"I just wanted to be home, that's all. Besides, the smell of the alcohol was making me sick. There was no way in hell that I could have had any of it."

He turns off his lamp and kisses his girlfriend's temple, sliding his arm around her waist. "I wonder why. Are you feeling sick?"

"Not particularly." Clary shrugs into the dark. "Although I have been throwing up in the morning for the past week or so."

"Really?" Jace frowns. "Why is that?"

"Oh, I don't know." she says innocently. "It may be because I'm actually pregnant."

Jace blinks. "You're joking."

"I'm not." Clary laughs. "I just felt like you should be the first person to know—besides my mom, Luke, and Jonathan, of course."

"You're actually pregnant?" Jace props himself up on his elbow, peering through the darkness to look at her face.

"I'm actually pregnant." she's grinning.

Jace kisses her, smiling broadly, and after Clary settles back down against his chest, she says, "Well, it looks like I'll be the designated driver for the next eight months."

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><p><strong>I hope you enjoyed this very much! Please review and let me know what you thought!<strong>


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